1. Technical Field
The present invention relates to a head-mounted display device.
2. Related Art
There is known a technique called augmented reality (AR) for additionally presenting information to a real object, which is an object actually present in a real world, using a computer. The information displayed additionally to the real object in the augmented reality is called “virtual object” as well. A function of the augmented reality is implemented in, for example, a head mounted display (hereinafter referred to as “HMD” or “head-mounted display device” as well).
The HMD picks up an image of an outside scene with a camera, recognizes the image obtained by the image pickup, and generates or acquires a virtual object. A transmissive HMD, which does not block a visual field of a user in a mounted state of the HMD, causes the user to visually recognize only a virtual image including the virtual object. The user can experience the augmented reality by viewing both of the real object in the real world and the virtual object represented by the virtual image.
When the augmented reality is implemented in the transmissive HMD, to reduce a visual sense of discomfort given to the user, it is preferable to align the position of the real object visually recognized by the user and the position of the virtual object visually recognized by the user. The “position” includes a distance from the user and positions in the horizontal direction and the vertical direction within the visual field of the user. Therefore, in the related art, the position of the real object and the position of the virtual object are aligned by causing the left and right eyes of the user to visually recognize a virtual image including the virtual object given with a parallax.
However, human eyes have individual differences. In other words, positions of eyes, a shape of eyeballs, positions of parts related to the visual sense in the eyes (e.g., lenses, retinas, and central pits), and the like are different in each person. Therefore, even if the left and right eyes of the user are caused to visually recognize the virtual image including the virtual object given with the parallax in order to align the position of the real object and the position of the virtual object, if users are different, a shift occurs in positions of the virtual object visually recognized by the users. JP-A-2005-100366 (Patent Literature 1) describes a technique for detecting a visual line direction of a patient in a non-contact manner by image-processing a face image of the patient acquired by a video camera.
JP-A-2005-128901 (Patent Literature 2) is also an example of the related art.
In order to reduce the visual sense of discomfort given to the user in the augmented reality processing, it is preferable to determine the position of the virtual object taking into account the individual difference of the eyes. In this regard, the techniques described in Patent Literatures 1 and 2 do not take into account at all that the individual difference of the eyes is taken into account in the augmented reality processing.
Therefore, there is a demand for a head-mounted display device capable of implementing augmented reality processing that takes into account the individual difference of the eyes.